基于调制电磁脉冲场的主动电磁探测研究

在车辆检测中,主动电磁探测因其性能受环境干扰影响小而越来越受重视。但是主动电磁探测常采用连续波工作,车辆的反射信号与直耦信号叠加在一起,使得检测算法非常复杂。为了大幅度简化检测算法,提出了一种调制电磁脉冲场方法。本系统包括一个磁偶极子发射天线和一个接收线圈,发射天线持续地辐射经正弦信号调制的且极性周期性改变的脉冲信号,这样就产生了一个具有低频成分的发射电磁场。如果目标存在,在接收电磁场的脉冲间隔内,就会出现目标的涡流二次场。连续地在接收电磁场的脉冲间隔内采样并做谱,如果出现此低频成分,则表示目标存在。

Study of active EM detection based on EM modulated pulse field

In the vehicle detection,active electromagnetic detection is paid more attention because its performance is hardly affected by environmental interference.However,active electromagnetic detection usually transmits continuous sine wave,reflected signal from vehicle and coupling signal add together,thus detection algorithm is extremely complicated.In order to significantly simplify detection algorithm,this paper presents a electromagnetic modulated pulse field method.This system contains a magnetic dipole transmitting antenna and a receiving sensor.Transmitting antenna continuously radiates pulse signal modulated by sine wave,and the pulse signal’s polarity changes periodically.This results in emitted electromagnetic field which contains low frequency component.If metal target exists,there will be the eddy magnetic field of target in the receiving electromagnetic pulse interval.Continuously sampling in the receiving electromagnetic pulse interval and analyse its spectrum.If there is the low frequency component,then the target exists.